The present invention relates to a system for controlling ignition timing and fuel injection timing of a two-cycle engine at cold state, and more particularly to a control system for the two-cycle engine having an exhaust emission control system with a catalytic converter.
In a four-cycle engine, temperature of exhaust gas is high comparing with that of the two-cycle engine, so that a catalyst in the catalytic converter provided in an exhaust pipe is sufficiently heated to be activated for ensuring exhaust emission control.
In the two-cycle engine, however, a part of intake air escapes from a cylinder through an exhaust port at scavenging the cylinder. Thus, the temperature of the exhaust gas is lowered. In particular, in a low engine speed range and a light load range, the catalyst is not heated to an activated temperature. As a result, the exhaust gas containing poisonous elements is emitted to atmosphere.
In order to maintain the activated temperature of the catalyst, it is proposed to provide the catalytic converter at an upper stream portion of the exhaust pipe so that the exhaust gas having a high temperature may pass through the catalytic converter.
However, since the temperature of the exhaust gas is high in a full load range, durability and function of the catalyst are reduced.
On the other hand, Japanese Utility Model Application Laid-Open 62-124211 discloses a catalytic converter in which a heater is provided at an inlet thereof. The heater is adapted to change a heating value thereof in dependency on the temperature. It is effective to increase the temperature of the catalyst to the activated temperature. However, it consumes a large electric power, and it is difficult to heat the whole catalyst. Further, it is necessary to provide a control unit for heating the heater.